Aquatic Toxicology 163 (2015) 167–176 Contents lists available at ScienceDirect Aquatic Toxicology j ourna l ho me pa ge: www.elsevier.com/locate/aquatox The effects of salinity changes on the Polychaete Diopatra neapolitana: Impacts on regenerative capacity and biochemical markers Rosa Freitas a,∗ , Adília Pires a , Cátia Velez a , Ângela Almeida a , Frederick J. Wrona a,b , Amadeu M.V.M Soares a , Etelvina Figueira a a Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal b Department of Geography, University of Victoria, 8500 Finnerty Road, David Turpin Building, Victoria, BC V8P 5C2, Canada a r t i c l e i n f o Article history: Received 19 December 2014 Received in revised form 31 March 2015 Accepted 4 April 2015 Available online 6 April 2015 Keywords: Rainy and drought periods Biomarkers Oxidative stress Polychaetes Redox status a b s t r a c t Polychaetes have been identified by several authors as a group of marine invertebrates that respond rapidly to anthropogenic stressors. However, studies investigating alterations in Polychaetes affected by climate changes are scarce. Thus, the present study aimed to assess the impact of salinity changes (14, 21, 28, 35, 42 g/L) on the physiological and biochemical performance of the Polychaete Diopatra neapolitana, evaluating the species regenerative ability and biochemical alterations. The results obtained demonstrated that organisms exposed to extreme salinity conditions (14, 21 and 42 g/L) presented higher mortality rates, needed more days to completely regenerate the missing body region and also regenerated less chaetigers, when compared to organisms exposed to salinities 28 and 35 g/L. The present study further demonstrated that D. neapolitana presented significantly lower glycogen and protein content at salinities 21 and 42 g/L, which can be explained by higher energy expenditure in the physiological and biochemical processes. A marked impairment of the glutathione redox status was also recorded at salinities 21 and 42 g/L. Increased antioxidant enzyme activities were observed at salinity 21 g/L while LPO levels were increased at salinity 42 g/L. Overall the present study demonstrated that the regenerative capacity of D. neapolitana can be used as a tool to assess environmental changes, namely salinity shifts. Moreover, stress related biomarkers revealed to be useful to evaluate the alterations in Polychaetes due to salinity changes. D. neapolitana revealed to be a good bioindicator to salinity alterations. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Coastal marine habitats are of major importance as they house a large number of benthic species with considerable economic and ecological importance, which makes these environments a major object of concern regarding the predicted global alterations (e.g., climate change, biological invasions, the presence of emergent con- taminants). In recent years, there has been an upsurge of attention in climate change impacts in coastal systems, with most of the liter- ature being focused on the effects of temperature (e.g., Chen et al., 2007; Harley et al., 2006; Hiebenthal et al., 2013; Monari et al., 2007) and water acidification (e.g., Barros et al., 2013; Dupont et al., 2013; Range et al., 2011; Timmins-Schiffman et al., 2013). However, ∗ Corresponding author at: Departamento de Biologia, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal. Tel.: +351 234370782; fax: +351 234372587. E-mail address: rosafreitas@ua.pt (R. Freitas). there is also concern about the effects of future alterations in seawa- ter salinity, mainly in estuarine areas (Cardoso et al., 2008; Kay et al., 2006; Matozzo and Marin, 2011; Reid et al., 2003). Frequent flood events are hypothesized to lead to prolonged periods of reduced salinity with increased frequency in estuarine areas (Bussell et al., 2008). Recent studies revealed that rainfall events are increasing on average worldwide, which in marine coastal systems may act as a disturbing agent, promoting responses of organisms. In fact, studies have shown that increases above usual rainfall levels may strongly decrease environmental salinity with implications for the functioning of ecosystem (Cardoso et al., 2008; Chollett and Bone, 2007; Norkko et al., 2002; Salen-Picard and Arlhac, 2002; Salen- Picard et al., 2003; Zajac and Whitlatch, 2003). Besides extreme rainy events, salinity shifts in aquatic systems can also be a conse- quence of drought periods, related to the reduction of freshwater inputs into estuaries, with effects at the community level. Attrill et al. (1996) investigated the effect of low flows on tidal freshwater macroinvertebrates at the head of an estuary and noted dramatic changes in community composition with small increases in salinity. http://dx.doi.org/10.1016/j.aquatox.2015.04.006 0166-445X/© 2015 Elsevier B.V. All rights reserved.